Crystals, Volume 13, Issue 10 (October 2023) – 121 articles

New complexes of manganese(II) hexafluoroacetylacetonate [Mn(hfac)₂] with 2-(1-R-3-pyrazol-4-yl)-4,4,5,5-tetramethyl-2-imidazoline-3-oxide-1-oxyl (R = CHF₂, CH₂CH₂F, CH₂CHF₂ or CH₂CF₃) were synthesised and characterised structurally and magnetically. All complexes were prepared under similar conditions. Nonetheless, their crystal structures were considerably different. Depending on the structure of fluorinated alkyl substituent R, the complexation reaction led to complexes of three types: chain-polymeric complexes with the head-to-head or head-to-tail motif and complexes of molecular structure. All complexes show strong antiferromagnetic behaviour in a high-temperature region (150–300 K) and weak ferro- or antiferromagnetic exchange interactions at low temperatures. The stronger antiferromagnetic exchange, −101.7 ± 1.5 or −136 ± 10 cm⁻¹, −82.3 ± 1.3 cm⁻¹ and −87.4 ± 1.3 cm⁻¹, was attributed to the magnetic interaction in three- or two-spin clusters: {>N∸O–Mn²⁺–O∸N<} or {>N∸O–Mn²⁺}, respectively. The weaker antiferromagnetic interaction, −0.005, between three-spin clusters or ferromagnetic interactions, 0.18–0.81 cm⁻¹, between two-spin clusters are realised through the pyrazole ring or intermolecular contacts. Full article

The major challenge of hydrogen production via photocatalytic water-splitting is to utilize active photocatalysts that respond to a wide range of visible light. In this work, hybrid nanostructures purposed to combine the tunable magnetic behavior of soft/semi-hard magnetic particles have shown advantageous photoactivity. A series of photocatalysts based on ferrite nanoparticles, magnetite nanoparticles (MNPs), cobalt ferrite nanoparticles (CFNPs), magnetite nanoparticles coated on cobalt ferrite nanoparticles (MNPs @ CFNPs), and cobalt ferrite nanoparticles coated on magnetite nanoparticles (CFNPs @ MNPs) were prepared. The size, morphology, magnetic properties, and optical activity of the prepared nanoparticles were characterized using multiple techniques. CFNPs @ MNPs had the largest particle size (~14 nm), while CFNPs had the smallest (~8 nm). The saturation magnetization of CFNPs @ MNPs was the highest at 55.45 emu g⁻¹. The hydrogen yield was 60, 26, 3.8, and 93 mmole min⁻¹ g⁻¹ for MNPs, CFNPs, MNPs @ CFNPs, and CFNPs @ MNPs. CFNPs @ MNPs displayed a superior photocatalytic performance for hydrogen production under the magnetic force as appropriate materials for water-splitting processing. Full article

One of the important areas of research in the energy sector is the study of the prospects for using new types of nuclear fuel, including tritium, which is one of the most promising types of fuel for thermonuclear energy. At the same time, for the production of tritium in the required quantities, the one that is the most optimal is the use of blanket materials based on lithium-containing ceramics. This is where tritium is released from lithium under the influence of neutron irradiation. The paper presents the results of an investigation of the influence of two-phase ceramics based on Li₄SiO₄–Li₂TiO₃ compounds on the resistance to external influences (mechanical loads) during the accumulation of hydrogen and helium (He²⁺) in the near-surface layer. The interest in such studies is primarily related to the search for solutions in the field of creating high-strength materials for tritium generation for its further use as nuclear fuel for thermonuclear fusion, as well as to the study of the mechanisms of the influence of different phases on the changes in the strength properties of ceramics, which provides an opportunity to expand fundamental knowledge in this area. The proposed method of obtaining two-phase ceramics by mechanical-chemical mixing and subsequent sintering into spherical particles enables the production of well-structured, high-strength ceramics of specified geometric dimensions (limited only by the dimensions of the mold) with a controlled phase ratio. During the experiments, it was found that increasing the content of Li₄SiO₄ phase in ceramics leads to an increase in strength characteristics (hardness, resistance to cracking) by 15–20% compared to single-phase ceramics. The most optimal composition of two-phase ceramics with high resistance to destructive embrittlement is the ratio of phases 0.75Li₄SiO₄–0.25Li₂TiO₃. One of the factors explaining the increase in resistance to destructive embrittlement under high-dose irradiation for two-phase ceramics is the increased dislocation density and the presence of interphase or intergranular boundaries, the high concentration of which leads to the creation of additional obstacles to the agglomeration of hydrogen and helium in the near-surface layer. Full article

The high-pressure growth technique generally plays an important role in the improvement of sample quality and the enhancement of various physical and magnetic properties of materials. The high gas pressure technique provides a large sample space (10–15 cm) to grow various kinds of materials. In this paper, we introduce the high gas pressure and high-temperature synthesis (HP-HTS) technique that is present at our institute and is applied to the growth process of different kinds of superconducting materials, particularly iron-based superconductors. More details and the working principle of this HP-HTS technique are discussed. We have also demonstrated the current results based on iron-based superconductors by using this unique HP-HTS technique. These results demonstrate the enhancement of the superconducting properties with improved sample quality compared to the conventional synthesis process at ambient pressure. Full article

Quasi-beta processing was considered to be a promising processing method to obtain a component with excellent mechanical properties. To achieve an optimized quasi-beta processing parameter for TC21 alloys, the hot deformation behavior in the near β phase region for the alloy with a forged structure was investigated by the thermal compression test and finite element (FEM) simulation. The obtained results indicated that the flow behavior of the samples was significantly influenced by the hot deformation parameters, and it exhibited a flow hardening behavior at the start stage of deformation. Based on the experimental data, the constitutive equation and processing maps were obtained. The optimum hot processing parameter was 986 °C/10⁻³ s⁻¹. Based on the FEM simulation results, the evolution of the temperature field, strain field, and stress field in the deformed samples at different strains exhibited a similar trend in the unstable region, which was distributed symmetrically along the center line of the samples, with the center area of the samples being the highest and the center area of the section being the lowest. Full article

The adsorption equilibrium of methane (CH₄) and carbon dioxide (CO₂) on the metal–organic framework (MOF) UiO-66 is studied via molecular simulation. UiO-66 is a versatile MOF with vast potential for various adsorption processes, such as biogas upgrading, CO₂ capture, and natural gas storage. The molecular simulations employ the grand canonical Monte Carlo (GCMC) method, covering a temperature range of 298–343 K and pressures up to 70 bar for CH₄ and 30 bar for CO₂. The accuracy of different forcefields in describing the adsorption equilibria is evaluated. Two modelling approaches are explored: (i) lumping each hydrogen atom in the MOF framework to the heavy atom it is bonded to (united atom approximation) and (ii) considering explicit hydrogen atoms. Additionally, the influence of electrical charges on CO₂ adsorption is also evaluated. The findings indicate that the most effective forcefield to describe the adsorption equilibrium is a united atom forcefield based on the TraPPE parametrization. This approach also yields an accurate calculation of the isosteric heat of adsorption. In the case of CO₂, it is observed that the use of electrical charges enhances the prediction of the heat of adsorption, especially in the low-coverage region. Full article

Due to notable water–salt activities, salt damage easily recurs and becomes one of the biggest challenges for the protection of ancient murals. Herein, superhydrophobic SiO₂ materials with different sizes were used to modify mural ground layer substrates, and the improvement effect mechanisms were systematically evaluated with scanning electron microscopy (SEM), X-ray diffraction (XRD), laser scanning confocal microscopy (LSCM), and a contact angle instrument. The results show that the superhydrophobic SiO₂ can spread into the substrates though holes and cracks and further increase the contact angles of the substrates to water droplets. Compared with the initial ground layer substrate, the substrates treated with the superhydrophobic SiO₂ possess stronger mechanical strength and a better ability in suppressing water–salt activity. In particular, larger-size SiO₂ (mSiO₂) maintains better mechanical reinforcement in the substrates, because mSiO₂ can provide better support in the internal gaps of the substrates. By contrast, nSiO₂ can spread deeper into the substrate than mSiO₂, and more greatly improve the contact angle to water droplets, endowing nSiO₂ with a better ability to restrain water–salt activity. Our study provides an alternative idea for solving salt damage in murals, and promotes the application of SiO₂ materials in heritage conservation. Full article

In this paper, a relationship between the structure and the electrical properties of a nanocrystalline composite ceramics xNa₂O·(100 − x)V₂O₅ with ‘x’ of 5, 15, 25, 35, and 45 mol%, abbreviated as xNV, was investigated by X-ray diffractometry (XRD), X-ray absorption spectroscopy (XAS), Cyclic Voltammetry (CV), Electrochemical impedance spectroscopy (EIS), and cathode active performance in Na-ion battery (SIB). For the expected sodium vanadium bronzes (Na_xV₂O₅) precipitation, the preparation of xNV was performed by keeping the system in the molten state at 1200 °C for one hour, followed by a temperature decrease in the electric furnace to room temperature at a cooling rate of 10 °C min⁻¹. XRD patterns of the 15NV ceramic exhibited the formation of Na_0.33V₂O₅ and NaV₃O₈ crystalline phases. Moreover, the V K-edge XANES showed that the absorption edge energy of ceramics 15NV recorded at 5479 eV is smaller than that of V₂O₅ at 5481 eV, evidently indicating a partial reduction from V⁵⁺ to V⁴⁺ due to the precipitation of Na_0.33V₂O₅. In the cyclic voltammetry, reduction peaks of 15NV were observed at 1.12, 1.78 V, and 2.69 V, while the oxidation peak showed up only at 2.36 V. The values of the reduction peaks were related to the NaV₃O₈ crystalline phase. Moreover, the diffusion coefficient of Na⁺ (D_Na⁺) gradually decreased from 8.28 × 10⁻¹¹ cm² s⁻¹ to 1.23 × 10⁻¹² cm² s⁻¹ with increasing Na₂O content (x) from 5 to 45 mol%. In the evaluation of the active cathode performance of xNV in SIB, ceramics 15NV showed the highest discharge capacity 203 mAh g⁻¹ at a current rate of 50 mA g⁻¹. In the wider voltage range from 0.8 to 3.6 V, the capacity retention was maintained at 50% after 30 cycles, while it was significantly improved to 90% in the narrower voltage range from 1.8 to 4.0 V, although the initial capacity decreased to 56 mAh g⁻¹. It is concluded that the precipitation of the Na_0.33V₂O₅ phase improved the structural and electrical properties of 15NV, which provides a high capacity for the Na-ion battery when incorporated as a cathode active material. Full article

Dual-wavelength output devices have a wide range of applications in mid-infrared band difference frequency generation, anti-interference lidar, dual-wavelength holographic interferometry, and other applications. Vertical external cavity surface-emitting lasers (VECSELs) are a type of semiconductor laser that can achieve single-chip dual-wavelength output by designing the chip structure. In this paper, we present a single-chip VECSEL that can switch between dual-wavelength and single-wavelength output modes. The VECSEL can simultaneously emit coaxial laser beams at 967 nm and 1013 nm, with a wavelength spacing of about 45 nm. The degree of mismatch between the gain peaks of the two quantum wells in the gain chip and the corresponding cavity modes is different. By adjusting the pump power, the temperature of the active region can be changed, which alters the matching relationship between the gain peaks and the cavity modes and controls the output mode of the VECSEL. The dual-wavelength output mode maintains a stable wavelength spacing at different operating temperatures. The laser output mode can be switched between single-wavelength and dual-wavelength, and the beam divergence angle is less than 8°. The dual-wavelength output power can exceed 400 mW, and the long-wavelength output power can reach up to 700 mW. Full article

Crystallization is the limiting step in X-ray structure determination of biological macromolecules. As crystallization experiments can be largely automatized, the diversity of precipitant solutions is often the determinant factor to obtain crystals of high quality. Here, we introduce a 96-well screening kit of crystallization conditions, centered on three ethoxylate-based organic polymers as precipitants and various additional compounds to promote crystal formation. This crystallization screen was tested on various non-standard proteins from bacteria and archaea. Structure determination succeeded for seven out of thirteen targets based on crystals that frequently diffracted to a higher resolution than those obtained with commercially available screening kits. Crystallization hits were rarely similar among the three ethoxylate-based organic polymers and, in comparison, with already available crystallization screens. Hence, the presented crystallization screen is an efficient tool to complement other screens and increase the likelihood of growing crystals suitable for X-ray structure determination. Full article

Salt hydrates are highly promising materials for thermochemical energy storage applications to store waste heat below 200 °C. Although highly researched and theoretically promising, in practical applications salt hydrates often cannot fulfill expectations. Based on the promising results of the Ca-oxalate monohydrate/Ca-oxalate system, other Ca-dicarboxylate salt hydrates were investigated to determine whether potential materials for heat storage can be found amongst them. A simultaneous thermal analysis showed that all candidates are applicable in the temperature range of 100–200 °C, and thermally stable up to 220 °C. Calcium malonate dihydrate (637 J/g), calcium terephthalate trihydrate (695 J/g), and tetrafluoro calcium terephthalate tetrahydrate (657 J/g) have shown higher enthalpies of dehydration than Ca-oxalate monohydrate. Due to the investigation of derivatives of Ca-terephthalate, it is possible to report the crystal structure of 2-fluoro calcium terephthalate. In single crystals, it forms a trihydrate and crystallizes in the Pmna space group (Z = 4, Z’ = ½) forming infinite chains of Ca atoms. De- and rehydration reactions of the most promising candidates were studied in situ with powder X-ray diffraction showing the structural changes between the hydrate and anhydrate states. Full article

In this study, we utilized a dielectric Bragg reflector (DBR) as a mirror and positioned a wide-spectrum FAMACsPb(BrI)₃ halide perovskite film between two DBRs to construct a vertical-cavity surface-emitting laser (VCSEL) structure. The top and bottom DBRs were connected using optical adhesive, allowing us to control the cavity length by applying external force. Through this approach, we achieved operation at the desired wavelength. Due to the exceptional optical gain provided by FAMACsPb(BrI)₃, we successfully observed multimode and lasing phenomena at room temperature under continuous-wave (CW) laser excitation. The outcomes of this study provide valuable insights for the application of novel VCSEL structures and highlight the potential of using FAMACsPb(BrI)₃ halide perovskites in optical gain. This work holds significant implications for the fields of optical communication and laser technology. Full article

High-performance sintered Nd-Pr-Fe-B magnets were successfully prepared by depositing Dy/Tb films on the surface using magnetron sputtering, which resulted in superior grain boundary diffusion (GBD) under heat treatments. The course of the diffusion was assessed using an electron probe microanalyzer (EPMA) and inductively coupled plasma (ICP). The magnetic properties and thermal stability of the magnets before and after diffusion were investigated. The results show that, mainly due to the increased and optimized Nd-Pr-rich phases and the formation of the (Nd,Pr,Dy/Tb)₂Fe₁₄B shell structure surrounding the (Nd,Pr)₂Fe₁₄B grains, the coercivity of the Dy- and Tb-diffused magnets was enhanced from 16.7 kOe to 24.8 kOe and 28.4 kOe, respectively, while the corresponding maximum energy product (BHmax) was 48.1 MGOe and 48.5 MGOe, respectively. The consumption of Dy/Tb in this work (0.35 wt% Dy in the Dy-diffused magnet and 0.42 wt% Tb in the Tb-diffused magnet) is much lower than that of previously reported magnets with comparable coercivity. Furthermore, Dy- or Tb-diffused magnets exhibit better thermal stability than that of the original magnet, owing to the better resistance to thermal disturbances of the magnets with optimized microstructure. This work can provide useful guidance for preparing Nd-Fe-B magnets with low cost and high performance. Full article

A series of xylene charge-transfer complexes with fluorine-substituted tetracyanoquinodimethane (TCNQ) acceptors were studied experimentally and theoretically in order to reveal the role of various intermolecular interactions on stoichiometry and the crystal structure. It was shown that o-xylene face-to-face donor–donor interactions became significant enough to result in the formation of 2:1 cocrystals with F₁TCNQ and F₄TCNQ irrespective of growth conditions. The supramolecular arrangement in these cocrystals is mainly determined by the number of fluorine atoms in the acceptor. Comparative DFT and MP2 calculations of the pairwise intermolecular interactions revealed the overestimation of the dispersion energy for these systems by the DFT-wB97XD approach. Full article

This article examines the processes of structure formation occurring during joint plastic deformation by the explosion of copper and molybdenum. These components are dissimilar metals with very limited mutual solubility under normal conditions, and the circumstances allowing for their interaction, as well as the products of the mechanochemical reactions of such interactions, have not been sufficiently studied and require new approaches. A cluster approach was used to describe the processes of structure formation, which describes phase formation as the process transitioning of the polyhedron of the initial phase into the polyhedron of the final phase. This work shows that under the conditions under consideration, not only is the formation of solid solutions in the contact zone with smooth concentration transitions from one component to another possible, but also the formation of new structural states, which can be represented as localized icosahedral atomic configurations (amorphous metal clusters). Such a structure is capable of locally strengthening the composite, which is confirmed by microhardness studies. Full article

As the name implies, patient-specific latticed hip implants vary in design depending on the properties required by the patient to serve as a valid suitable organ. Unit cells are typically built based on a 3D design of beams, and the properties of unit cells change depending on their geometries, which, in turn, are defined by two main parameters: beam length and beam thickness. Due to the continuous increase in the complexity of the unit cells’ designs and their reactions against different loads, the call for machine learning techniques is inevitable to help explore the parameters of the unit cells that can build lattice structures with specific desirable properties. In this study, a machine learning technique is used to predict the best defining parameters (length and thickness) to create a latticed design with a set of required properties (mainly porosity). The data (porosity, mass, and latticed area) from the properties of three unit-cell types, applied to the latticed part of a hip implant design, were collected based on the random length and thickness for three unit-cell types. Using the linear regression algorithm (a supervised machine learning method) from the scikit-learn library, a machine learning model was developed to predict the value of the porosity for the lattice structures based on the length and thickness as input data. The number of samples needed to generate an accurate result for each type of unit cell is also discussed. Full article

Roseolumiflavin is a deep red microcrystalline derivative of isoalloxazine that exhibits a weak photophysical activity in the solid state. In aqueous as well as in acidic solution of formic or acetic acid, respectively, it tends to form solvates. Herein, we present a set of binary and ternary roseolumiflavin solvates including one hydrate and a solvate hydrate. The impact of the solvent on solvate formation along with an in-depth structural analysis was investigated. Calculations of the lattice energies provide insight into the phase stability of the evaluated systems showing an energetic benefit for all solvates with values up to −395.82 kJ/mol. The total interaction energies between molecules calculated via Crystal Explorer further identified cofacial π···π stacks to be the most strongly bonding fragments in the crystal lattices for all systems except the formic acid solvate, followed by remarkably weaker hydrogen-bonded arrangements. The energetic contributions of single intermolecular interactions within the fragments are evaluated by an atoms-in-molecules approach. It is shown that physicochemical properties, such as thermal stability, can be tuned depending on the incorporated solvent molecules despite a high decomposition temperature of the chromophore. Full article

Perovskite oxide heterostructures have provided opportunities for new technologies and materials with novel properties.In particular, researchers have been interested in the magnetism and two-dimensional electron gases that form at the interface of many of these heterostructures. Often, these properties are due to polar discontinuities, but here we use first-principles calculations to examine a heterostructure whose elements, EuO and EuTiO${}_3$, are both non-polar, yet are still conductive due to oxygen vacancies. Furthermore, the free electrons at the interface of this heterostructure are predicted to be spin-polarized, opening up possibilities for future research and devices. Full article

The Schmid factor (SF) is a critical parameter in crystal plasticity research that is often used to evaluate the level of difficulty in activating the slip systems within a grain. The evolution process and change mechanism of SF in 316 austenitic stainless steel during plastic deformation were investigated in this paper by using the in situ electron backscatter diffraction (EBSD) technique. The results showed that the average Schmid factor of global grains was highest in the original state, but after stretching, multiple rotation paths appeared in the grain, and the SF presented a monotonically decreased tendency with the increase in plastic strain degree. Numerical computation revealed that the decrease of SF was mainly governed by the change in φ angle, i.e., the angle between loading direction and slip plane normal increased inside the grains after the lattice rotation, which caused the slip plane to move parallel to the loading direction. The higher φ, the lower its cosine, which corresponds to low shear stress acting on the slip plane and could increase the difficulty of crystal slip. Full article

A low-cost and high-efficiency solid reaction method has been reported as an effective technology to synthesize manganese ferrite MnFe₂O₄ with a spinel crystal structure. This work clarified the underlying reason for the influence mechanism of SiO₂ and Al₂O₃ on the synthesis of MnFe₂O₄. Synthetic MnFe₂O₄ polyhedral microparticles with a saturated magnetization of 71.19 emu/g, a ratio of saturation magnetization to residual magnetization (Ms/Mr) of 0.062 and a coercivity (Hc) of 6.50 Oe were successfully obtained at an oxidization roasting temperature of 1100 °C for 60 min. The experimental results indicate that the tetrahedral Mn²⁺ ions and octahedral Mn³⁺ ions in the crystal structure of manganese ferrite MnFe₂O₄ were replaced by tetrahedral Si²⁺ ions and octahedral Al³⁺ ions from (Mn²⁺)_x(Fe²⁺)_y(Si²⁺)_1−x−y[Fe³⁺]₂O₄ and (Mn²⁺)[Fe³⁺]_2−x[Al³⁺]_xO₄, respectively. In addition, hercynite Fe_xMn_1−xAl₂O₄ with a spinel crystal structure and olivine Mn_xFe_2−xSiO₄ with an orthorhombic crystal structure were partially formed in the synthesis of manganese ferrite MnFe₂O₄, in which some Fe²⁺ ions were easily replaced by Mn²⁺ ions to form stable hercynite MnAl₂O₄ and olivine Mn₂SiO₄ in these crystal structures. The current research work provides comprehensive insights for synthesizing manganese ferrite MnFe₂O₄ and continuously advances its technical progress. Full article

The lattice dynamical properties of dilute InAs_1−xN_x/InP (001) epilayers (0 ≤ x ≤ 0.03) grown by gas-source molecular beam epitaxy were carefully studied experimentally and theoretically. A high-resolution Brüker IFS 120 v/S spectrometer was employed to measure the room-temperature infrared reflectivity (IRR) spectra at near-normal incidence (θ_i = 0). The results in the frequency range of 180–500 cm⁻¹ revealed accurate values of the characteristic In-As-like and In-N-like vibrational modes. For InAs_1−xN_x alloys, a classical “Drude–Lorentz” model was constructed to obtain the dielectric functions $\tilde{\mathsf{\epsilon }}\left(\mathsf{\omega }\right)$ in the far IR regions by incorporating InAs-like and InN-like transverse optical ${\mathsf{\omega }}_{\mathrm{T}\mathrm{O}}$ modes. Longitudinal optical ${\mathsf{\omega }}_{\mathrm{L}\mathrm{O}}$ phonons were achieved from the imaginary parts of the simulated dielectric loss functions. The theoretical results of IRR spectra for InAs_1−xN_x/InP (001) epilayers using a multi-layer optics methodology provided a very good agreement with the experimental data. At oblique incidence (θ_i ≠ 0), our study of s- and p-polarized reflectance (R_s,p(ω)) and transmission (T_s,p(ω)) spectra allowed the simultaneous perception of the ${\mathsf{\omega }}_{\mathrm{T}\mathrm{O}}$ and ${\mathsf{\omega }}_{\mathrm{L}\mathrm{O}}$ phonons of the InAs, InN and InAs_0.97N_0.03 layers. Based on the average t-matrix Green’s function theory, the results of local vibrational modes for light ${\mathrm{S}\mathrm{i}}_{\mathrm{I}\mathrm{n}}^{+}$ donors and ${\mathrm{S}\mathrm{i}}_{\mathrm{A}\mathrm{s}}^{-}, {\mathrm{C}}_{\mathrm{A}\mathrm{s}}^{-}$ acceptors in InAs were found in good agreement with the existing Raman scattering and infrared spectroscopy data. $\mathrm{I}\mathrm{n}\mathrm{I}\mathrm{n}\mathrm{N}$, however, the method predicted an in-band mode for the ${\mathrm{M}\mathrm{g}}_{\mathrm{I}\mathrm{n}}^{-}$ acceptor while projecting an impurity mode of the ${\mathrm{S}\mathrm{i}}_{\mathrm{I}\mathrm{n}}^{+}$ donor to appear just above the maximum ${\mathsf{\omega }}_{\mathrm{m}\mathrm{a}\mathrm{x}}^{\mathrm{I}\mathrm{n}\mathrm{N}}[\equiv 595 {\mathrm{c}\mathrm{m}}^{-1}$] phonon frequency region. In InAs_1−xN_x/InP (001) epifilms, the comparison of reflectivity/transmission spectra with experiments and the predictions of impurity modes for isoelectronic donor and acceptor impurities in InAs and InN can be valuable for appraising the role of defects in other technologically important semiconductors. Full article

To promote the efficient utilization of bulk solid wastes, including superfine river sand and fly ash, high-flowing steel-fiber-reinforced mixed-sand concrete (SFRMC) was developed in this study. Superfine river sand and coarse manufactured sand were mixed in a proportion of 4:6 to make the mixed sand. Fly ash, with a content of 30~75%, was blended with 0~12% silica fume on the premise of equivalent activity. The water dosage and sand ratio were adjusted with the volume fraction of steel fiber, which varied from 0.4 to 1.6%, to ensure the high flowability of fresh SFRMC. The mechanical properties, including cubic and axial compressive strengths, modulus of elasticity, splitting tensile strength, and flexural strength and toughness of the SFRMC, were analyzed, accounting for the influences of the contents of fly ash and steel fiber. The predictive formulas for the splitting tensile strength, modulus of elasticity, and flexural strength were proposed by introducing the influencing factors of steel fiber. The SFRMC showed an increased modulus of elasticity with increases in the steel fiber factor, and flexural toughness was enhanced with increased contents of both steel fiber and fly ash. Full article

Here, we report on using chemical vapor deposition to generate three kinds of gallium sulfide nanosheets, with thicknesses of approximately 10, 40, and 170 nm. Next, we performed Raman imaging analysis on these nanosheets to evaluate their properties. The 10 nm GaS nanosheets exhibited a nearly equal distribution of Raman imaging intensity, whereas the 40 and 170 nm GaS nanosheets exhibited an inclination toward the edges with higher Raman intensity. When the polarization of the laser was changed, the intensity of Raman imaging of the 10 nm thick GaS nanosheets remained consistent when illuminated with a 532 nm laser. Notably, a greater Raman intensity was discernible at the edges of the 40 and 170 nm GaS nanosheets. Three distinct GaS nanosheet devices with different film thicknesses were fabricated, and their photocurrents were recorded. The devices were exposed to light of 455 nm wavelength. The GaS nanosheet devices with film thicknesses of 40 and 170 nm exhibited a positive photoresponse even though the photocurrents were fairly low. In contrast, the GaS nanosheet device with a film thickness of 10 nm had a considerable current without light, even though it had a weak reaction to light. This study reveals the different spatial patterns of Raman imaging with GaS thickness, the wavelength of excitation light, and polarization. Remarkably, the I-V diagram revealed a higher dark-field current of 800 nA in the device with a GaS nanosheet thickness of approximately 10 nm, when using a voltage of 1.5 V and a laser of 445 nm wavelength. These findings are comparable with those theretical pretictions in the existing literature. In conclusion, the observation above could serve as a catalyst for future exploration into photocatalysis, electrochemical hydrogen production through water splitting, energy storage, nonlinear optics, gas sensing, and ultraviolet selective photodetectors of GaS nanosheet-based photodetectors. Full article

Fe-Mn-Al-Ni is an Fe-based shape memory alloy (SMA) featuring higher stability and low temperature dependency of superelasticity stress over a wide range of temperatures. Additive manufacturing (AM) is a promising technique for fabricating Fe-SMA with enhanced properties, which can eliminate the limitations associated with conventional fabrication and allow for the manufacture of complicated shapes with only a single-step fabrication. The current work investigates the densification behavior and fabrication window of an Fe-Mn-Al-Ni SMA using laser powder bed fusion (LPBF). Experimental optimization was performed to identify the optimum processing window parameters in terms of laser power and scanning speed to fabricate Fe-Mn-Al-Ni SMA samples. Laser remelting was also employed to improve the characteristics of Fe-Mn-Al-Ni-fabricated samples. Characterization and testing techniques were carried out to assess the densification behavior of Fe-Mn-Al-Ni to study surface roughness, density, porosity, and hardness. The findings indicated that using a laser power range of 175–200 W combined with a scanning speed of 800 mm/s within the defined processing window parameters can minimize the defects with the material and lead to decreased surface roughness, lower porosity, and higher densification. Full article

A new molecular conductor, i.e., κ-(BEDT-TTF)₂K⁺(18-crown-6)[Co^II(NCS)₄]∙(H₂O), is semiconductive with substantial charge gap values (ΔE) of 0.57 eV (measured) and 0.37 eV (calculated). There is a full band separation despite formal average charge on BEDT-TTF of +0.5 and κ(kappa)-type packing of BEDT-TTF dimers that favors high conductivity. X-ray crystal structure analysis reveals complete charge ordering with full Coulomb charge on unique BEDT-TTF radical cations A (Q_A = +1), while unique molecules B are uncharged (Q_B = 0). Geometries of A (flat) and B (bent) differ considerably and are in accordance with the ascribing charges. Charge segregation is enhanced by forming tight face-to-face BEDT-TTF dimers AA (Q_AA = +2) and BB (Q_BB = 0). Strongly interacting double-charged dimers AA form “superstripes” running along a that are interleaved along b with chains of neutral dimers BB. Peculiar extremely thick (13.7 Å) four-decker insulating anion layers cast strong Coulomb potential onto the conductive layers predetermining charge localization in the latter. Full article

The binary Zn-1wt.% X (X = Mg or Sr) alloys prepared by the application of mechanical alloying (MA) combined with powder metallurgy were modified by micro-arc oxidation (MAO) treatment in the 2 g/dm³ KOH aqueous solution at 200 V for 1 min for the formation of the ZnO layer. The Zn-alloys, obtained through the powder metallurgy method, are characterized by a dispersive microstructure that significantly improves its microhardness up to 90.5 HV_0.3 for the Zn-1wt.%Mg sample after 24 h of MA. In the case of Zn-1Mg alloy after 24 h of mechanical alloying, Zn-1Mg alloy after 48 h of mechanical alloying, and Zn-1Sr alloy after 48 h of mechanical alloying, except for the main αZn phase, the traces of a second phase are noticed: MgZn₂ and SrZn₁₃. After the proposed MAO treatment, a zinc oxide (ZnO) layer on the zinc alloys was formed, allowing a significant improvement in the corrosion resistance and surface wetting properties. The potential of the modified ZnO layer is moved to more noble values in the case of MAO-treated samples α-Zn, Zn-1Mg (after 24 h of MA), and Zn-1Sr (after 48 h of MA). The obtained results show a good prospective potential of Zn-1wt.% X (X = Mg or Sr) binary alloys in the application of biodegradable materials. Full article

There are numerous methods used for measuring the coefficient of thermal expansion of alloys and density change at low temperatures, but it is difficult to accurately measure the volume and density of high-temperature melts, particularly during the process of rapid volume change during material phase transformation. This article proposes a method for measuring and analysing the volume and density changes in high-temperature alloy melts using high-speed photography and computer MATLAB program image analysis technology, which includes the ordinary image threshold segmentation method, the elliptical fitting method, and the local dynamic threshold segmentation method. The ordinary image threshold segmentation method is best suited to samples with clear boundaries; the elliptical fitting method is the simplest and can be used to analyse samples with unclear boundaries; and the local dynamic threshold segmentation method is the most accurate and best suited to samples with unclear boundaries. These techniques will aid in understanding the variations in the volume and density of high-temperature melt samples during the phase transition process. Full article

Adsorption of gas molecules on the surface of two-dimensional (2D) molybdenum disulfide (MoS₂) can significantly affect its carrier transport properties. In this letter, we investigated the effect of a vacuum environment on the electrical properties of a back-gate MoS₂ FET. Benefiting from the reduced scattering centers caused by the adsorbed oxygen and water molecules in a vacuum, the current I_on/I_off ratio of back-gate MoS₂ field effect transistor increased from 1.4 × 10⁶ to 1.8 × 10⁷. In addition, the values of field effect carrier mobility were increased by more than four times, from 1 cm²/Vs to 4.2 cm²/Vs. Furthermore, the values of subthreshold swing could be decreased by 30% compared with the sample in ambient air. We demonstrate that the vacuum process can effectively remove absorbates and improve device performances. Full article

In this article, we employed the saturation voltage method (SVM) to investigate the interaction between a nematic liquid crystal (NLC) and a graphene oxide (GO) substrate. The SVM approach involved applying a potential difference (ΔV) to the cell containing the NLC (specifically, 5CB) to reorient the nematic director (n) from a parallel to a perpendicular configuration with respect to the cell’s surface. By utilizing sandwich cells with indium–tin oxide semi-transparent electrodes covered by GO, we measured the anchoring energy between the NLC and the thin GO film. To evaluate the strength of this anchoring energy, we compared the results with two other cells: one exhibiting strong anchoring energy (polyimide cell) and the other demonstrating weak anchoring energy (formvar cell). The influence of GO thin films on the alignment of nematic 5CB was distinctly observed. Full article

DFT-D3 calculations based on structural X-ray diffraction data obtained for 3-oxo-camphorsulfonyl imine (1), camphorsulfonyl chloride (2) and seven camphor sulfonimines (O₂SNC₁₀H₁₃NR, L¹−L⁷), from which L² (R=4-OHC₆H₄), L⁴ (R=4-ClC₆H₄) and L⁶ (R=3,5-(CH₃)₂C₆H₃) are synthesized and characterized in this work, provide information into the intra- and inter-molecular interactions with concomitant elucidation of the supramolecular arrangement of the compounds. The DFT-D3 calculations performed in small clusters of two or three molecular units reproduce the interactions observed via X-ray analyses, showing that, as a general trend, the structural arrangement of the molecules is driven by electronic rather than by packing parameters. In all compounds, the self-assembly of 3D structures involves the sulfonyl imine group (-NSO₂) either to establish hydrogen bonds through oxygen atoms or non-classic oxygen–aliphatic hydrogen or non-bonding interactions (NBIs), which also involve sulfonyl oxygen atoms. Interestingly, the camphor sulfonimine compounds (L², L³), having protic groups (R=C₆H₄X:X=OH, L² or X=NH₂, L³) at the aromatic imine substituents (=NR), present an extra π-π stacking, which is absent in the other compounds’ aromatic derivatives. The X-ray analysis shows that all the reported camphor sulfonimine compounds display the E configuration with respect to the imine substituent (R). The study of the redox behavior of the compounds by cyclic voltammetry enables insight into the solution properties of the compounds and the rationalization of the molecular interactions that stand in the solid and solution states. Camphor sulfonimine compounds (L) display appropriate binding atoms to coordinate transition metals. The results herein show that monodentate coordination through the nitrogen atom of the sulfonimine five-membered ring to the {Ag(NO₃)} metal center is favored. When this imine nitrogen atom is not itself involved in the organic framework, DFT-D3 calculations show that the complexation does not affect the non-covalent interactions that are reproduced in the MOF structure. Full article